Critical information about the first fatal shooting by the PSNI was deleted from a police computer before the Police Ombudsman could see it, it emerged today.
Nuala O'Loan cleared the police officer who shot and killed 21-year-old Neil McConville more than four years ago as he drove a murderer through the countryside with a sawn off shotgun.
But in a statement today she expressed "grave concern" about other aspects of the case.
Mrs O'Loan said the operation that led to McConville's death on April 29, 2003, was "poorly managed by senior officers".
She also said that one of the PSNI's most senior officers tried to block her investigators from getting access to intelligence material about the shooting.
And when they were allowed to see it - more than six weeks after the shooting - a piece of intelligence "critical to the investigation" had been deleted from a police computer.
" Despite seizing the relevant computer hard drive and securing expert assistance, it proved impossible to recover the information" a statement from her office said.
"There was no evidence to either support or disprove the police explanation of human error for the deletion of the information."
Mrs O'Loan said: "People may have great difficulty accepting the explanation offered ? particularly following the resistance to granting access to the material."
She said a police officer had prepared a written note covering the deleted information, but "it was not possible to check its accuracy". The Ombudsman recommended action against some officers she said had failed to co-operate with her investigation - saying two officers should be transferred to "less contentious areas of policing". She also revealed that several senior officers who may have been subject to discipline retired before her investigation could be completed.
And Mrs O'Loan recommended that most PSNI weapons should be adapted to stop them from firing automatically - because the officer who killed McConville meant to fire a single shot but ended up hitting him with a burst of three shots.
She said she first made this recommendation almost three years ago, in response to another shooting incident.
Neil McConville became the first person killed by the PSNI when he was shot three times as he tried to drive away from police.
He had been stopped in his car after a chase on the Aghalee Road near Ballinderry, outside Lisburn, as police were trying to track his passenger, David Somers. Police had intelligence that Somers was about to shoot a person when the operation was mounted.
Mrs O'Loan confirmed that the officer who opened fire believed McConville was about to drive over another officer who had been knocked down and was lying injured in front of his car.
An unloaded sawn-off shotgun was found in the car. Somers was convicted last month for aiding and abetting possession of the gun. He is already serving a sentence for murdering a man in north Belfast six weeks before Neil McConville was shot.
Mrs O'Loan criticised a senior policeman's decision to order officers to stop the Vauxhall Cavalier driven by McConville "from behind". Mrs O'Loan said she had "no criticism" of the officer who fired the fatal shots.